A variety of power generator systems are known. A difficulty with such power generator systems may arise when the required duty cycle involves supplying instantaneous power while cycling on and off with very short pulse durations. UPS (uninterruptable power supply) systems require a genset and an energy storage device such as a battery, capacitor, or flywheel to provide instantaneous power response to ensure that a building computer or telephone system are not impacted by a power outage. These UPS systems add complexity and increase cost, weight, and maintenance requirements to the genset.